A210892 -id:A210892 - cp's OEIS frontend

A210893 Dates after Jan 01 1000 in chronological order which are palindromic when they are written according to the format MMDDYYYY (American standard). Leading zeros of the terms are suppressed.

10011001, 1011010, 11011011, 2011020, 12011021, 3011030, 4011040, 5011050, 6011060, 7011070, 8011080, 9011090, 10111101, 1111110, 11111111, 2111120, 12111121, 3111130, 4111140, 5111150, 6111160, 7111170, 8111180, 9111190, 10211201, 1211210, 11211211, 2211220, 12211221

Offset: 1

Hieronymus Fischer, Apr 01 2012

There are exactly 331 such palindromic dates between Jan 1 1000 and Dec 31 9999 (see b-file for the complete list).
Dates palindromic in the MMDDYYYY format are also palindromic in the YYYYMMDD format. Consequently, this sequence represents the same dates as A210884.
See A210883 for the number of days after Jan 1 1000 to get such a palindromic date.
The first such palindromic dates after Jan 01 2000 are 10022001, 1022010, 11022011, 2022020, 12022021, 3022030, 4022040, 5022050, 6022060, 7022070, 8022080, 9022090, 10122101, which are the 44th, 45th, ... 56th ... dates of the original sequence.

			The first palindromic date in MMDDYYYY format after 'Jan 01 1000' is a(1)=10011001 (= 'Oct 01 1001' = 'Jan 01 1000' + A210893(1) days);
The second palindromic date in MMDDYYYY format after 'Jan 01 1000' is a(2)=1011010=01011010 (= 'Jan 01 1010' = 'Jan 01 1000' + A210893(2) days);
The 47th palindromic date in MMDDYYYY format after 'Jan 01 1000' is a(47)=2022020=02022020 (= 'Feb 02 2020' = 'Jan 01 1000' + A210893(47) days).
The last (331st) palindromic date in MMDDYYYY format before the year 10000 is a(331)=9299290=09299290 (= 'Sep 29 9290' = 'Jan 01 1000' + A210893(331) days).

Hieronymus Fischer, Table of n, a(n) for n = 1..331

Cf. A210883 - A210892, A210894 - A210895, A106605, A107273, A107275.

a(n)=MMDDYYYY_date('Jan 1 1000' + A210883(n)).

n-th date after 'Jan 1 2000' = a(43+n).

A210890 Dates after Jan 01 00 in chronological order which are palindromic when they are written in the format D.M.YY. The terms are listed as numbers (without the dots).

Original entry on oeis.org

10101, 10201, 10301, 10401, 10501, 10601, 10701, 10801, 10901, 101101, 20102, 20202, 20302, 20402, 20502, 20602, 20702, 20802, 20902, 201102, 30103, 30303, 30403, 30503, 30603, 30703, 30803, 30903, 301103, 1111, 11111, 11211, 11311, 11411, 11511, 11611, 11711

Offset: 1

Hieronymus Fischer, Apr 01 2012

There are exactly 322 such palindromic dates between Mar 1 00 and Dec 31 99 (see b-file for the complete list).
See A210889 for the number of days after 'Mar 1 00' to get such a palindromic date.
The definition is different from A210892 in that the dates are considered as numbers.
Some numbers occur twice since the dates are not unique without the dots. For example, the number 11211 may represent the date 11.2.11 (Feb 11 11) or 1.12.11 (Dec 1 11). The complete list of such dates is 11.1.11, 11.2.11, 1.11.11, 1.12.11, 21.1.12, 21.2.12, 2.11.12, 2.12.12, 31.1.13 and 3.11.13 which correspond to the terms with n=31,32,41,43,45,46,55,57,59 and 65.

			The first palindromic date in D.M.YY format after 'Jan 01 00' is a(1)=10101 (= '10.1.01' = 'Jan 10 01' = 'Mar 01 00' + A210889(1) days);
The 10th palindromic date in D.M.YY format after 'Jan 01 00' is a(10)=101101 (= '10.11.01' = 'Nov 10 01' = 'Mar 01 00' + A210889(10) days);
The 44th palindromic date in D.M.YY format after 'Jan 01 00' is a(44)=2112 (= '2.1.12' = 'Jan 2 12' = 'Mar 01 00' + A210889(44) days);
The last (322nd) palindromic date in D.M.YY format after 'Jan 01 00' is a(322)=9999 (= '9.9.99' = 'Sep 09 99' = 'Mar 01 00' + A210889(322) days).

Hieronymus Fischer, Table of n, a(n) for n = 1..322

Cf. A210883-A210889, A210891-A210895, A106605, A107273, A107275.

a(n) = DMYY_date('Mar 1 00' + A210889(n)).

A210891 Number of days after Mar 01 00 such that the date written in the format D.M.YY is palindromic.

Original entry on oeis.org

315, 346, 374, 405, 435, 466, 496, 527, 558, 619, 690, 721, 749, 780, 810, 841, 871, 902, 933, 994, 1065, 1124, 1155, 1185, 1216, 1246, 1277, 1308, 1369, 3968, 3999, 4027, 4058, 4088, 4119, 4149, 4180, 4211, 4272, 4343, 4374, 4403, 4434, 4464

Offset: 1

Hieronymus Fischer, Apr 01 2012

There are exactly 214 such palindromic dates between Jan 1 00 and Dec 31 99 (see b-file for the complete list).
The definition is different from A210889/A210890 in that the palindrome property is evaluated including the dots.
See A210892 for the corresponding dates.
The reference date Mar 1 00 makes sense, since this definition results in a sequence which is independent from the leap year / non-leap year property of the reference year '00'.

			The first palindromic date in D.M.YY format after 'Jan 01 00' is A210892(1)=10101 (='10.1.01'= 'Jan 10 01' = 'Mar 01 00' + 315 days);
The 10th palindromic date in D.M.YY format after 'Jan  01 00' is A210892(10)=101101 (='10.11.01'= 'Nov 10 01' = 'Mar 01 00' + 619 days);
The 44th palindromic date in D.M.YY format after 'Mar 01 00' is A210892(44)=21512 (='21.5.12'= 'May 21 12' = 'Mar 01 00' + 4464 days);
The last (214th) palindromic date in D.M.YY format after 'Mar 01 00' is A210892(214)=291192 (='29.11.92'= 'Nov 29 92' = 'Mar 01 00' + 33876 days).

Hieronymus Fischer, Table of n, a(n) for n = 1..214

Cf. A210883 - A210890, A210892 - A210895, A106605, A107273, A107275

cp's OEIS Frontend

A210893 Dates after Jan 01 1000 in chronological order which are palindromic when they are written according to the format MMDDYYYY (American standard). Leading zeros of the terms are suppressed.

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A210890 Dates after Jan 01 00 in chronological order which are palindromic when they are written in the format D.M.YY. The terms are listed as numbers (without the dots).

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A210891 Number of days after Mar 01 00 such that the date written in the format D.M.YY is palindromic.

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